JPH10250182A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the print quality and the paper carrying performance by providing a thermal line head with an automatic centering mechanism movable up and down or in the rotational direction about a part of the side plate of a printer base located farther in the paper discharge direction than the thermal line head. SOLUTION: The heat radiating plate 32 of a thermal line head 18 is normally charged, on the rear side thereof, by a head push spring 34 secured to the bottom face of a printer base 31 by means of a screw 33, or the like. When a paper 17 to be transferred is pressed against a platen 7, the securing part of the stepped screw 29a, 29b at an automatic centering mechanism section 23a, 23b is moved upward along an elongated hole 24a, 24b made in a side plate 30a, 30b and the paper 17 is pressed uniformly against the forward end of the thermal line head 18. Upon occurrence of paper jam under that state, a printer cover 3 is opened and a paper release lever 5 is operated to lower the supporting part 27 of each automatic centering mechanism section 23a, 23b in the rotational direction thus releasing contact between the thermal line head 18 and the paper 17 to be transferred.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer, and more particularly, to equalizing a load for pressing paper (transferred paper) sandwiched between a thermal line head and a round platen, or smoothing in conjunction with a paper release lever. The present invention relates to a thermal line head automatic alignment mechanism having a simple paper release mechanism.

[0002]

2. Description of the Related Art In a general thermal printer, when a thermal line head is pressed onto a round platen via paper, the thermal line head is disposed on a strong member, and either the thermal line head or the round platen is disposed. Is pressed with a load of 3 kgf or more by a plurality of coil springs or leaf springs.

[0003] Since there are a plurality of springs, each spring is fixed at a predetermined position.

[0004]

The conventional printer has a large product size, and a plurality of springs can be used.

The thermal line head is pressed uniformly by a plurality of springs to prevent the thermal line head from hitting one side, so that printing quality and paper transport performance can be stably performed.

[0006] With the spread of portable information terminal devices and the like, there is an increasing need for small and thin portable thermal printers as output devices.

The present invention is directed to a small and thin portable thermal printer.

A small and thin portable thermal printer has a printer size of about 180 mm in width, about 120 mm in depth, about 22 mm in height, and the height of the thermal line head assembly (5 to 6 mm).
No) and the diameter of the round platen is small (about 9mm)
Ultra-compact structure, aluminum plate that also serves as the heat sink for the heat-sensitive line head (the plate thickness:
About 4-5mm) and thin.

The printer base is a steel plate, but the thickness is as thin as about 1 mm.

At first, in order to improve the printing quality, the pressing pressure of the thermal line head was set at about 3 kgf, but there was a problem that the printer base was deformed like a bow.

That is, it is difficult to incorporate a plurality of springs or coil springs having a height, and to set a pressing pressure of the heat-sensitive line head of 3 kgf or more.

Experiments have shown that in the product structure of the present invention, the printer base is not deformed unless the pressure of the thermal line head is reduced to 1.38 (kgf).

The deformation of the printer base causes the pressure distribution of the thermal line head to become unstable, and the pressure on the transfer receiving paper becomes unstable. When printing is performed, density unevenness occurs in characters and the like, and the print quality is deteriorated. Cause.

[0014] Also, in the transport of paper, the surface pressure on the paper surface changes, causing paper skew in which paper is transported diagonally.

[0015] The problem to be solved by the present invention is to eliminate the one-side contact of the thermal line head. Because the thermal printer is small, thin and portable, and the space inside is small, when the thermal line head is pressed with a spring member, the pressing force of the thermal line head becomes non-uniform.
One-sided phenomena of the thermal line head occur.

The printing density is high when hitting hard, and low when hitting weakly. That is,
Density unevenness occurs in printed characters and the like, which causes deterioration in print quality.

Further, the one-side contact phenomenon of the heat-sensitive line head is such that the surface pressure against the paper surface changes even when the paper is conveyed,
This causes a paper skew phenomenon in which the paper is conveyed diagonally.

The present invention focuses on the above, and when a paper such as a thermal paper or a double copy paper is pressed against a round platen by a thermal line head, the paper is always uniform with respect to the paper such as the thermal paper or the double copy paper. Pressure can be applied to prevent uneven contact of the thermal line head, which causes uneven density of printed characters and paper skew phenomenon in which paper such as thermal paper or two sheets of paper is conveyed diagonally. The thermal printer has been designed to reduce the size and thickness of the printer by making it possible to completely prevent the paper jam and to easily release the paper with a smooth operation even when clearing the paper jam. It is intended to provide.

If this object is achieved, it is possible to provide a small and thin portable thermal printer with stable printing quality and paper transport performance. Further, the structure is simple, and cost reduction can be expected.

[0020]

In order to achieve the above object, the present invention comprises a thermal line head and a round platen, and prints on the paper sandwiched between the thermal line head and the round platen by the thermal line head. In the thermal printer, an automatic centering mechanism of the thermal line head that holds the thermal line head assembly is provided, and the automatic centering mechanism is configured to partially remove the printer base side plate in the paper discharging direction from the position of the thermal line head. It is provided with an automatic alignment mechanism that can be moved vertically or rotationally as a center.

A notch is provided at the upper part of the side plate of the self-aligning mechanism located at the center of the shaft of the round platen, so that the movable side plate of the self-aligning mechanism does not contact the shaft of the round platen. The operation is performed in accordance with the operation of the release lever.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIGS.
This will be described with reference to FIGS.

FIG. 1 is a perspective view of a main part of a thermal line head self-aligning mechanism of the present invention, FIG. 2 is an exploded perspective view of the thermal printer showing an overall structure of the thermal printer of the present invention, and FIG. FIG. 4 is a perspective view of a main part showing a structure of a movable fulcrum of the thermal line head automatic alignment mechanism of the present invention. FIG. 4 is a view showing a movable fulcrum state when the paper release lever is operated in the thermal line head automatic alignment mechanism of the present invention. FIG. 5 is a front view showing an application example of the self-aligning mechanism in the present invention.

First, the overall structure of the thermal printer of the present invention will be described with reference to FIG.

In the figure, reference numeral 16 denotes a connector for connecting the information processing apparatus with a cable, and print data and the like are transmitted from the information processing apparatus to the printer via the connector 16.

In the case of printing, first, the power switch 12 is turned on, and a paper to be transferred, such as thermal paper or two-copy paper, is passed through the paper sensor 8 and inserted from the paper insertion unit 20.
It is set between the round platen 7 and the thermal line head 18. These papers are not only papers which themselves react to heat and develop a black color, but may also be plain papers which are transferred via an ink ribbon.

Next, the paper supply / discharge switch 13 is pressed to feed a transfer paper such as a thermal paper or a two-sheet copy paper by an automatic paper feeding mechanism (hereinafter, referred to as auto loading), and the paper is caught. Wait for printing to start.

For automatic loading of transfer paper such as thermal paper or two-copy paper, a signal is sent to the control board 4 by pressing the paper supply / discharge switch 13, and a signal is sent from the control board 4 to the line feed motor 10. The line feed motor 10 is operated.

The rotation of the line feed motor 10 is
To rotate the round platen 7 to move a transfer paper such as a thermal paper or a two-sheet copy paper between the thermal line head 18 and the round platen 7 to a reference position for cueing.

The transfer of a transfer sheet such as a thermal paper or a two-sheet copy paper is smoothly performed by pressing the paper against the round platen 7 from below with a leaf spring (not shown) against the thermal line head 18. Like that.

Thereafter, when a print start command is input from the information processing apparatus, the control board 4 rotates the round platen 7 and simultaneously applies heat to a plurality of heating resistors (not shown) of the thermal line head 18. A paper guide integrated with the main body upper case 2 by transferring the transfer paper such as the heat-sensitive paper or the two-sheet copying paper while the surface of the transfer paper such as the heat-sensitive paper or the two-sheet copying paper is colored and printed by this heat. The paper is discharged through the top of the printer cover 3 through 19 and printing is completed.

On the control board 4, a CPU (Central Pro
A processing unit (central processing unit) 21, a motor driver IC, an IC for driving the thermal line head 18, and the like are arranged.

The heat-sensitive line head 18 and the line feed motor 10 are controlled by the CPU 21.

The printer cover 3 is supported by a paper release lever 5 and a screw. By inclining the printer cover 3 as shown in the figure, the gap between the heat-sensitive line head 18 and the round platen 7 is enlarged, and trouble such as paper jam occurs. Occasionally, it is possible to take out a transfer paper such as a thermal paper or a two-sheet copy paper having a jam.

Reference numerals 6a and 6b denote finger guides, which are provided so that they can be operated smoothly when the paper release lever 5 is tilted.

Reference numeral 14 denotes a power ON / OFF indicator lamp.

Reference numeral 1 denotes a lower case of the main body, in which a control board 4, a printer main body and the like are disposed. The upper body case 2 is fixed to the lower body case 1 from the back surface of the printer body by fastening members such as screws.

Reference numeral 15 denotes a secondary battery, which is a drive power source for the control board 4, the line feed motor 10, the thermal line head 18, and the like. The secondary battery 15 is detachable from the upper case 2 of the main body.

Reference numeral 11 denotes an alarm lamp, which is provided so that the lamp blinks when there is no paper or an abnormality occurs in the printer function.

Reference numeral 22 denotes a paper alignment guide, which is provided integrally with the paper release lever 5. The paper alignment guide 22 has a function of aligning the leading end of the paper at the contact position between the thermal line head 18 and the round platen 7 when feeding the paper. When a transfer paper such as a thermal paper or a two-copy paper is conveyed, the transfer paper such as the thermal paper or the two-copy paper is pressed by a single leaf spring from the lower side of the thermal line head 18. The platen 7 is conveyed by being pressed against it.

Next, an automatic centering mechanism of the thermal line head according to the present invention will be described with reference to FIG.

FIG. 1 shows a state in which the paper release lever is operated and the automatic alignment mechanism of the thermal line head 18 is moving.

Reference numerals 23a and 23b are thermal line head automatic alignment mechanisms. The self-aligning mechanisms 23a and 23b of the thermal line head 18 are provided with a head assembly fixing surface 25 for mounting and fixing the thermal line head 18 assembly and a head assembly fastening hole 26 for fixing the thermal line head 18 assembly. , Screw holes 43 for holding the stepped screws 29a and 29b, and a notch 2 for avoiding contact of the round platen 7 with the shaft 41.
8. Support 2 for interlocking the operation of paper release lever 5
7 and the like.

When the paper release lever 5 is not operated in the printing state, the head pressing spring 34 fixed to the bottom surface of the printer base 31 with a fastening member such as a screw 33 causes the back surface of the heat radiating plate 32 assembled with the heat-sensitive line head 18 to be assembled. When the transfer paper 17 such as heat-sensitive paper or two sheets of paper is pressed against the surface of the round platen 7, the self-centering mechanism 23a, 2
3b stepped screws 29a, 29b are fixed to the side plate 30a,
It moves upward at the slots 24a and 24b provided in 30b, and the transfer paper 17 such as thermal paper or two-sheet paper is pressed uniformly by the tip of the thermal line head 18.

When a paper jam such as a sheet 17 to be transferred such as thermal paper or two sheets of paper is stuck in the transport path, the printer cover 3 is opened, and the paper release lever 5 is operated. The support portions 27 of both the self-aligning mechanism portions 23a and 23b are lowered in the direction of the arrow in association with the paper release lever 5, ie, in the rotational direction with the stepped screws 29a and 29b as the fulcrum. And the contact with the transfer receiving paper 17 such as thermal paper or two-copy paper is released.

Next, the operation of the fulcrum of the self-aligning mechanism 23b in the printing state will be described with reference to FIG.

The self-aligning mechanism 23b is pushed up in the direction of arrow A by pressing the thermal line head. or,
The self-aligning mechanism 23b moves up and down minutely in response to printing on thick transfer paper such as two sheets of paper or fluctuations in the pressure of the thermal line head due to variations in the accuracy of the mechanism.

The structure is such that a stepped screw 29b is fixed to the screw hole 36 of the self-aligning mechanism 23b so that an oval long hole such as 24b is passed through the side plate 30b.
This is a structure in which the stepped portion 35 moves up and down the long hole 24b.

Next, the operating state of the fulcrum when the paper release lever is operated will be described with reference to FIG.

When the paper release lever is operated, the self-aligning mechanism 23b moves in the direction indicated by the arrow C in conjunction therewith.

Accordingly, the stepped screw 29b moves in the direction D of the arrow in the direction D of the arrow in parallel with the elongated hole 24b provided in the side plate 30b.

The stepped screw 29b moves to the upper part of the long hole 24b provided in the side plate 30b, and the stepped portion 3 of the stepped screw 29b is formed at the upper R portion of the long hole 24b provided in the side plate 30b.
It hits on five sides.

Thereafter, the self-aligning mechanism 23b further moves the stepped portion 3 in the direction of arrow C with the surface of the stepped portion 35 as a fulcrum.
It moves while rotating around five surfaces.

FIG. 5 shows an application of the present invention, in which a projection 39 is provided in place of the stepped screw and a recess 40 is provided in place of the slot provided in the side plate.

A recess formed by extruding a steel plate is provided on the side plate 30a of the printer base 31, and the projection 39 formed by extruding the steel plate on the side surface of the self-aligning mechanism 23a is moved up and down in the recess of the recess. This is a structure in which the entire self-aligning mechanism 23a is moved downward while rotating as a fulcrum.

[0056]

As described above, according to the present invention, when paper such as thermal paper or two-copy paper is pressed against the round platen by the thermal line head, paper such as thermal paper or two-copy paper is obtained. Can always apply a uniform pressing force to the print head, preventing the thermal line head from colliding with one another. This makes it possible to generate unevenness in the density of printed characters and to transfer paper such as thermal paper or two-copy paper diagonally. The skew phenomenon can be prevented, and the paper can be easily released by smooth operation even when paper jam is cleared. In addition, the structure of the self-aligning mechanism is made thinner, so that the printer is smaller and thinner. It is possible to provide a type printer.

Further, it is possible to provide a small and thin portable thermal printer with stable printing quality and stable paper transport performance.
Further, the structure is simple, and cost reduction can be expected.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part showing a heat-sensitive line head automatic alignment mechanism of the present invention.

FIG. 2 is an exploded perspective view of the thermal printer showing the overall structure of the thermal printer of the present invention.

FIG. 3 is a perspective view of a main part showing a structure of a movable fulcrum of the thermal line head automatic alignment mechanism of the present invention.

FIG. 4 is a perspective view of a main part showing a movable fulcrum state when a paper release lever is operated in the thermal line head automatic alignment mechanism of the present invention.

FIG. 5 is a front view showing an application example of the self-aligning mechanism in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lower case of main body, 2 ... Upper case of main body, 3 ... Printer cover, 4 ... Control board, 5 ... Paper release lever, 6a, 6b ...
Finger guide, 7: Round platen, 8: Paper sensor, 9: Gear, 10: Line feed motor, 11: Alarm lamp, 12: Power switch, 13: Feed / discharge switch, 14
... Power ON / OFF indicator lamp, 15 ... Secondary battery, 16
... connector, 17 ... transfer paper, 18 ... thermal line head, 19 ... paper guide, 20 ... paper insertion unit, 21 ... CPU,
22: paper alignment guide, 23a, 23b: self-aligning mechanism, 24a, 24b: elongated hole, 25: head assembly fixing surface,
Reference numeral 26: head assembly fastening hole, 27: support, 28: notch, 29a, 29b: stepped screw, 30a, 30b: side plate, 31: printer base, 32: heat sink, 33: screw, 34: head Push spring, 35: stepped portion, 36: screw portion, 37: bearing, 38: E-ring, 39: protrusion, 4
0: recess, 41: shaft, 42: screw, 43: screw hole.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Ryoichi Kobayashi, 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Prefecture Inside the Taga Headquarters, Electrical Equipment Division, Hitachi, Ltd. (72) Inventor Akira Akutsu, Higashitaga, Hitachi City, Ibaraki Prefecture 1-1-1, Machi-cho, Hitachi Tachiga Engineering Co., Ltd. (72) Inventor, Toshimitsu Gomita 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Pref. Taga Headquarters, Hitachi, Ltd.

Claims (11)

[Claims] 1. A thermal printer comprising a thermal line head and a circular platen, wherein the thermal line head prints on paper sandwiched between the thermal line head and the circular platen. A self-aligning mechanism for the head is provided.This self-aligning mechanism is an automatic centering mechanism that can move up and down or in the direction of rotation about a part of the printer base side plate in the paper discharging direction from the position of the thermal line head. A thermal printer. 2. A thermal printer comprising a thermal line head and a round platen, wherein the thermal line head prints on paper sandwiched between the thermal line head and the round platen, wherein a long hole is provided in a side plate of the printer base. A fastening member such as a stepped screw is fastened from the outside of the side plate of the printer base to the side of the heat-sensitive line head fixing member so as to penetrate the long hole, and the heat-sensitive line head fixing member is vertically moved around the long hole. Or a thermal printer that can move in the direction of rotation. 3. The thermal printer according to claim 1, further comprising a heat-sensitive line head assembly fixing surface provided on a part of a movable side plate of the self-aligning mechanism, and a back surface of the heat-sensitive line head assembly fastened. A thermal printer with a structure that is fixed to the bottom of the self-aligning mechanism with a member. 4. The thermal printer according to claim 1, wherein the self-aligning mechanism is provided on one or both sides of the printer base. 5. The thermal printer according to claim 3, wherein a notch is provided near an upper portion of the self-aligning mechanism located at the center of the shaft of the round platen, and the movable side plate of the self-aligning mechanism and the circular plate are provided. Thermal printer with platen shaft not touching. 6. A thermal printer comprising a thermal line head and a round platen, wherein the thermal line head prints on paper sandwiched between the thermal line head and the round platen, wherein a concave portion is provided on an inner surface of a side plate of the printer base. A mechanism is provided on the side surface of the heat-sensitive line head fixing member to move the inner surface of the concave portion, and the mechanism moves vertically or rotationally around the protrusion in accordance with the fluctuation of the heat-sensitive line head load. Equipped thermal printer. 7. The thermal printer according to claim 6, wherein the concave portion on the inner surface of the side plate of the printer base and the projection of the side plate of the self-aligning mechanism are formed by extruding a thin steel plate. 8. The thermal printer according to claim 6, wherein the inner surface of the printer base side plate has a substantially oval shape, and is provided on the side plate surface of the self-aligning mechanism portion also serving as a heat-sensitive line head fixing member. A thermal printer in which the formed projection is located at the tip of the oval-shaped upper R portion of the recess when the paper release lever is operated. 9. A thermal printer comprising a thermal line head and a round platen, wherein when the thermal paper passes between the thermal line head and the round platen, heat is applied to the thermal paper by the thermal line head to cause the thermal paper to color and print. In the above, a thermal line head automatic alignment mechanism that holds the thermal line head assembly is provided, and this automatic alignment mechanism moves up and down around a part of the printer base side plate in the paper discharge direction from the position of the thermal line head. Or a thermal printer that is a self-aligning mechanism that can move in the direction of rotation. 10. A thermal printer comprising a thermal line head and a round platen, wherein when the thermal paper passes between the thermal line head and the round platen, heat is applied to the thermal paper by the thermal line head to cause the thermal paper to color and print. In the printer base, a concave portion is provided on the inner surface of the side plate, and a protrusion for moving the inner surface of the concave portion is provided on the surface of the side surface of the heat-sensitive line head fixing member. A thermal printer equipped with a mechanism that can move in the direction of rotation about a protrusion. 11. A heat-sensitive printer comprising a heat-sensitive line head and a round platen, wherein the heat-sensitive line head prints on paper sandwiched between the heat-sensitive line head and the round platen. A self-centering mechanism for the head is provided, and this self-centering mechanism is capable of moving vertically or rotationally around a part of the printer base side plate in the paper discharging direction from the position of the thermal line head. , Printer case size width 180
mm, depth about 120 mm, height about 22 mm and not more than this, the height of the thermal line head assembly should be about 5-6 mm and not more than this, and the diameter of the round platen should be about 10 mm and this Thermal printer with a diameter not exceeding.